Finite element analyses and design of post-tensioned anchorage zone in ultra-high-performance concrete beams

Abstract

This article presents analyses and the design of a post-tensioned anchorage zone made of ultra-high-performance concretes with three-dimensional finite element analyses. The structural behavior was investigated through the failure modes and cracking patterns to show the anchorage zone resistance enhancement with an increase of the strength in concrete. Since the anchorage failure is usually initiated from the local zone in the case of ultra-high-performance concrete beams that have compressive strength of more than 80 MPa, the placement of reinforcements can effectively be used to enhance the strength and ductility for the local zone. However, ultra-high-performance concrete requires a smaller amount of reinforcement than normal-strength concrete. Parametric analyses are carried out to show the effect of the spiral reinforcement on the strength of the anchorage zone, and comparison with the design guidelines in NCHRP Report 356 is made. Finally, improved guidelines are suggested to cover the design of ultra-high-performance concrete.